The rules module is a very powerful module that allows you to make things react in your site when certain events happen (like a comment has been made) under certain conditions (for example when the user has role x).

A lot of events, conditions and actions are allready out of the box or provided by some contrib modules who have rules integration.

How to submit some hidden values along with a drupal webform? Our example. We have job node (nid 1) and we want to go to a webform to apply for the job. So we build a link on our node pointing to the webform node (nid 2).
In the node template type quickly a url: node , nid webform, nid job node

A cck fieldgroup can be rendered alone. We had some quicktabs we wanted to fill with our field groups. So we've builded a block for each field group to put in the quicktabs. Here is an example of one block where we called a single fieldgroup and rendered it.

How to add another formatter to a cck field? A cck formatter is basically a theming function where the value of field is ran through. Formatters are available at "admin/content/node-type/[your node type]/display" in the cck interface.

How to load only the content fields of a node to avoid a full node load?

Sometimes in scripts you need information stored in cck fields but you dont want to do full node loads neither do you want to query the table directly because setting a field from single to multiple value would make the table location of that field change.